Low-temperature synthesis and characterization of ceria-based oxide ion conductors

Solid solutions of the general formula Ce_1–xLn_xO_2–x/2x/2 (Ln = lanthanide (III) and = anion vacancy), were prepared by a novel sol-gel route. These materials were characterized by powder diffraction and scanning electron microscopy. The gels formed on sol evaporation were found to be solid solutions with the fluorite structure and a crystallite size of approximately 6 nm. This is the lowest temperature of formation to date. The gels densified readily at 700 °C and the lattice parameter of these materials was found to be directly proportional to the ionic radius of the dopant.